Jason Mraz plants trees at Scottsdale Boys & Girls Club

For Jason Mraz, the road to planting trees outside the Scottsdale Boys & Girls Club's Rose Lane Branch began with a trip to Antarctica in February.

"I went with Al Gore and some friends," the pop singer says, "learning the doom and gloom of the climate crisis, and just feeling really confronted by how we live and how much energy we consume. I thought, 'You know, I could be doing more.'"

Mraz, whose biggest hit remains 2008's "I'm Yours," came home to San Diego and started working with a tree foundation there.

"And I thought I could add a little life to our tour by reaching out to tree groups in all the cities we play," he says. "I did it out of guilt, man."

Mraz's tree-planting program, presented in partnership with Reverb, a non-profit organization that encourages musicians and their fans to promote environmental sustainability, is called Tree is a Four Letter Word.

The name is a reference to "Love is a Four Letter Word," the singer's latest effort.

"We only called it that because of the album," Mraz says, with a smile. "I don't think a tree is a bad thing at all."

Mraz, who stopped in Scottsdale before his US Airways Center concert on Tuesday, Oct. 2, has planted trees in every city on the tour with one exception.

"We went to Austin in the dead of summer," he says. "It was not a good time to plant trees, so we did mulching."

The goal of the program, which includes inviting local tree groups to set up booths at every show, is to raise awareness of the importance of preserving the environment "so future generations can enjoy it."

Planting trees is not the only step Mraz has undertaken to offset his tour's carbon footprint.

"We're running all of our buses and trucks on biofuel," he says. "And everyone on our staff is using reusable water bottles. Even for our fans, they can come and get free water from our Brita refilling stations."

In Arizona, the musician teamed with the Arizona Community Tree Council and Mix 96.9, which offered listeners a chance to help Mraz plant trees.

"The coolest thing about this," morning DJ Mathew Blades says, "is so many people get hyped up on going backstage. But the backstage experience is overrated. Here's a cool opportunity to be face-to-face with somebody you really love doing something completely different."

Several kids who take part in the Boys & Girls Club's after-school program were also invited to the program Tuesday afternoon planting.

"It's exciting for the kids," says Cathy Cabezas, the Rose Lane Branch director, "especially when they see celebrities giving back to the community and volunteering. It's a good role model."

That sentiment is echoed by the kids themselves, including Olivia Benson, 9, of Scottsdale, who says, "It's great that he came out here because it shows other people that not all celebrities are, like, 'Oh, I just want to build another mansion' or 'I want a fancy car.' He came to Arizona and helped us plant some trees to help the universe."